Daily Archives: May 23, 2017

May 23, 2017 by Siv Schwink A 3-D graph depicting evolutionary trajectories constrained by a phenotypic trade-off. Credit: David T. Fraebel, U. of I. Department of Physics and Center for the Physics of Living Cells.

Organisms in nature adapt and evolve in complex environments. For example, when subjected to changes in nutrients, antibiotics, and predation, microbes in the wild face the challenge of adapting multiple traits at the same time. But how does evolution unfold when, for survival, multiple traits must be improved simultaneously?

While heritable genetic mutations can alter phenotypic traits and enable populations to adapt to their environment, adaptation is frequently limited by trade-offs: a mutation advantageous to one trait might be detrimental to another.

Because of the interplay between the selection pressures present in complex environments and the trade-offs constraining phenotypes, predicting evolutionary dynamics is difficult.

Researchers at the University of Illinois at Urbana-Champaign have shown how evolutionary dynamics proceed when selection acts on two traits governed by a trade-off. The results move the life sciences a step closer to understanding the full complexity of evolution at the cellular level.

Seppe Kuehn, an assistant professor of physics and member of the Center for the Physics of Living Cells at the U. of I., led the research. The team studied populations of the bacterium Escherichia coli, which can undergo hundreds of generations in a single week, providing ample opportunity to study mutations and their impact on heritable traits.

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The team selected populations of E. coli for faster migration through a porous environment. A quantitative model revealed that populations could achieve the fastest migration by improving two traits at onceswimming speed and growth rate (cell division).

Kuehn explains, "This study sheds new light on how evolution proceeds when performance depends on two traits that are restricted by a trade-off. Though a mathematical model suggests that the fastest migrating populations should be composed of cells that swim fast and reproduce quickly, what we found was that populations achieve faster migration through two divergent evolutionary paths that are mutually exclusive: in other words, these populations improved in either swimming speed or reproduction rate, but not both."

David T. Fraebel, a U. of I. graduate student in Kuehn's lab group, is lead author on the study. He comments, "Most experiments apply selection pressure to optimize a single trait, and trade-offs are observed in this context due to decay of traits that aren't being selected rather than due to compromise between multiple pressures. We selected for swimming and growth simultaneously, yet E. coli was not able to optimize both traits at once."

The selection environment created by the team determined which evolutionary trajectory the populations followed. In a nutrient-rich medium, faster swimming meant slower reproduction; in a nutrient-poor environment, however, slower swimming and faster reproduction led to the same desired outcome: faster migration through the porous environment.

By sequencing the DNA of the evolved populations, the team identified the mutations responsible for adaptation in each condition. When they genetically engineered these mutations into the founding strain, these cells demonstrated faster migration and the same phenotypic trade-off as the evolved strains.

"Our results support the idea that evolution takes the direction that's genetically easy," says Kuehn. "In a nutrient-rich environment, it's easy to find a mutation that enables the cells to swim faster. In a nutrient-poor environment, it's easy to find a mutation that makes cell division faster. In both cases, the mutations are disrupting negative regulatory genes whose function it is to reduce gene expression or protein levels."

"Other recent studies have shown that microevolution is dominated by changes in negative regulatory elements. The reason: it's statistically easy to find a mutation that breaks things versus one that builds new function or parts.

When selection acts on two traits restricted by a trade-off, the phenotype evolves in the direction of breaking negative regulatory elements, because it's an easy path statistically. It relates to the availability of useful mutations."

Kuehn summarizes the finding's value: "Improving predictive modeling of evolution will involve understanding how mutations alter the regulation of cellular processes and how these processes are related to trade-offs that constrain traits. Uncovering the general principles that define the relationship between regulation and trade-offs could enable us to predict evolutionary outcomes."

These findings are published in the online journal eLife.

Explore further: At molecular level, evolutionary change is unpredictable

More information: David T Fraebel et al. Environment determines evolutionary trajectory in a constrained phenotypic space, eLife (2017). DOI: 10.7554/eLife.24669

Biologists have been contemplating evolutionary change since Charles Darwin first explained it.

A new model exploring how evolutionary dynamics work in natural selection has found that phenotypic diversity, or an organism's observable traits, co-evolves with contingent cooperation when organisms with like traits work ...

Does evolution really trundle along like Darwin's famous Galapagos tortoise? And do the populations undergoing this evolution really grow and decline with the speed of a hare?

Higher organisms do not have a cost of complexity or slowdown in the evolution of complex traits according to a report by researchers at Yale and Washington University in Nature.

Biologists at the University of Pennsylvania studying the processes of evolution appear to have resolved a longstanding conundrum: How can organisms be robust against the effects of mutations yet simultaneously adaptable ...

For nearly 40 years, one of the cornerstones of the study of adaptation has been the examination of "whole-organism performance capacities"essentially, measures of the dynamic things animals do: how fast they can run; ...

Organisms in nature adapt and evolve in complex environments. For example, when subjected to changes in nutrients, antibiotics, and predation, microbes in the wild face the challenge of adapting multiple traits at the same ...

Biological engineers at Utah State University have successfully decoded and reprogrammed the biosynthetic machinery that produces a variety of natural compounds found in fungi.

Snakes, although as social as birds and mammals, have long been thought to be solitary hunters and eaters. A new study from the University of Tennessee, Knoxville, shows that some snakes coordinate their hunts to increase ...

The blue whale, which uses baleen to filter its prey from ocean water and can reach lengths of over 100 feet, is the largest vertebrate animal that has ever lived. On the list of the planet's most massive living creatures, ...

The spectacular variety of colours and patterns that butterflies use to ward off potential predators may result from highly localised environmental conditions known as "microhabitats", researchers have found.

Female vampire bats form strong social bonds with their mothers and daughters as they groom and share regurgitated meals of blood. They also form friendships with less closely related bats. Gerry Carter, post-doctoral fellow ...

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Genetic mutation trade-offs lead to parallel evolution - Phys.Org

May 23, 2017 Children taught genetics first increase their understanding of evolution. Credit: Miki Yoshihito, Flickr

Evolution is a difficult concept for many students at all levels, however, a study publishing on May 23 in the open access journal PLOS Biology has demonstrated a simple cost-free way to significantly improve students' understanding of evolution at the secondary level: teach genetics before you teach them evolution.

Currently in the UK setting the two modules are taught in isolation often with long time intervals between. The team, led by Professor Laurence Hurst at the Milner Centre for Evolution, University of Bath hypothesised that since core concepts of genetics (such as DNA and mutation) are so intimately linked to the core concepts of evolution, then priming students with genetics information might help their understanding of evolution.

The researchers conducted a large controlled trial of almost 2000 students aged 14-16 in 78 classes from 23 schools across the south and south west of the UK, in which teachers were asked to teach genetics before evolution or evolution before genetics.

The students were tested prior to teaching and after. The five year study, found that those taught genetics first improved their test scores by an average of seven per cent more than those taught evolution first.

Teaching genetics before evolution was particularly crucial for students in foundation classes, who increased their understanding of evolution only if they were taught genetics first. The higher ability classes saw an increase in evolution understanding with both orders, but it was greatest if genetics was taught first.

The team also tested the students' understanding of genetics and found that the genetics-first effect either increased genetics understanding as well or made no difference, meaning that teaching genetics first doesn't harm students' appreciation of this subject.

Professor Hurst, commented: "These are very exciting results. School teachers are under enormous pressure to do the best for their students but have little time to make changes and understandably dislike constant disruption to the curriculum."

"To be sensitive to their needs, in the trial we let teachers teach what they normally teach - we just looked at the order effect."

First author on the paper Dr Rebecca Mead, a former teacher herself, said: "It's remarkable that such a simple and cost-free intervention makes such a big difference. That genetics-first was the only intervention that worked for the foundation classes is especially important as these classes are often challenging to teach. This research has encouraged teachers to rethink how they teach evolution and genetics and many schools have now changed their teaching practice to genetics-first. I hope more will follow."

The team also looked at whether students in the study agreed or disagreed with the scientific view of evolution. They found that whilst the teaching of evolution increased acceptance rates to over 80 per cent in the cohort examined, the order of teaching had no effect.

Qualitative focus group follow-up studies showed that acceptance is heavily conditioned by authority figures (teachers, TV personalities, religious figures) and the correlation between the students' understanding of evolution and their acceptance of it is weak.

Dr. Mead commented: "Some students reported that being told that key authority figures approve of the scientific evidence for evolution made a big difference to their learning experience. It would be worth testing alternative ways to help students overcome preconceptions."

Explore further: Evolution and religion: New insight into instructor attitudes in Arizona

More information: Mead R, Hejmadi M, Hurst LD (2017) Teaching genetics prior to teaching evolution improves evolution understanding but not acceptance. PLoS Biol 15(5): e2002255. doi.org/10.1371/journal.pbio.2002255

Evolution can be an emotionally charged topic in education, given a wide range of perspectives on it. Two researchers from Arizona State University are taking an in-depth look at how college professors handle it.

College students' views about evolution and creationism are often shaped by what they learned in their high school biology classes, according to a University of Minnesota study published in the May issue of BioScience, the ...

University of Alabama at Birmingham (UAB) Associate Professor Lee Meadows, Ph.D., is author of a new book that claims it's possible to teach evolution without offending students who have strong religious convictions against ...

The Texas Board of Education will decide whether to scrap a requirement that public schools teach high school students to scrutinize "all sides" of scientific theory after hearing Tuesday from academics who say that was meant ...

High school and college students who understand the geological age of the Earth (4.5 billion years) are much more likely to understand and accept human evolution, according to a University of Minnesota study published in ...

South Dakota legislators are weighing whether to let teachers decide how much skepticism to work into lessons on contentious scientific topics such as evolution and climate change.

(Phys.org)The study of ancient civilizations, particularly those that did not leave extensive writing in the archaeological record, is reliant on the evidence of other kinds of material artifacts. And one of the keys to ...

(Phys.org)A trio of researchers with Columbia University has conducted a series of experiments regarding how much effort people are willing to exert in fact-checking news stories. In their paper published in Proceedings ...

A chance discovery in Mississippi provides the first evidence of an animal closely related to Triceratops in eastern North America. The fossil, a tooth from rocks between 68 and 66 million years old, shows that two halves ...

(Phys.org)A pair of researchers with the University of Massachusetts has found evidence that suggests women are more likely to continue to pursue a degree in engineering if they have a female mentor. Nilanjana Dasgupta, ...

How you dress, talk, eat and even what you allow yourself to feel - these often unspoken rules of a group are social norms, and many are internalized to such a degree that you probably don't even notice them. Following norms, ...

An archaeological study has found evidence of the earliest occupation of the Australian coast from Barrow Island, Northwest Australia.

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Improve evolution education by teaching genetics first - Phys.Org

A video appreciation of the action star weve always deserved.

Chris Pratt isnt just the action star we need right now, hes the action star weve always deserved. His characters have down-home charm in equal measure with good-natured braggadocio, they are as strong as they are vulnerable, capable as they are aloof, and dramatic as they are comedic. His swagger stumbles on occasion in the most likable of ways, and his weaknesses are a virtue for their ability to highlight his overwhelming humanity. Hes also, as Im told by my wife, frequently, quite easy on the eyes. You add all that up, and what you get is a template for a prototypical A-list action star; but Pratt is more than prototypical.

Because hes also a good man off-screen, one of faith who avoids the trappings and pitfalls of celebrity despite being one of the biggest movie stars on the planet. Hes a humble family man, and a man who wears his gratitude for his fortunes on his sleeve right next to his heart. Hes your neighbor, your buddy, your brother, your son, your dream boyfriend or BFF, an everyman we can all relate to, and a kind of success we can all aspire too: one that doesnt overtake your best qualities, rather one that amplifies them.

Am I being hyperbolic and a tad bit heavy-handed? Probably, but Chris Pratt is a rarity, the kind of movie star that doesnt come along just once in a blue moon, but once in a lifetime a movie star whose success isnt just a blessing to the industry, but to the community around him. I live in Washington State, where Pratt grew up, and when I hear about him on the local news, 9 times out of 10 it isnt about a movie hes in, its about some way in which he has reached out with his time and/or resources to someone in need. In an era where we celebrate culture and those who craft it probably a little more than we should, its comforting to me at least to know that theres someone in the spotlight willing to deflect it to worthier things.

This extreme likeability is what has made Pratts rise to superstardom so meteoric. From his first big role on the TV series Everwood to a third-tier supporting role on the first season of Parks and Rec that became a vital cog in one of the greatest comedy ensembles ever by series end, to his staggering big-screen success which is still in its infant stages weve cheered him on every step of the way not just because hes good at his job and fun to watch, but because we legitimately want him to do well, we want him to win, it just feels like a good thing for everybody.

All this to say, watching the following supercut from Burger Fiction on Pratts evolution to now is like watching the highlight reel of the first act of a great American success story, and better yet, one thats deserved.

Chris Pratt

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The Evolution of Chris Pratt - Film School Rejects

Trifling evidence and momentous conclusions. That is evolution in a nutshell, and news of the day from most mainstream sources bears out the observation once again. First, we learned that, on the basis of a lower jaw from Greece and an upper premolar from Bulgaria (Science Daily) a jaw and a tooth, thats it! were now supposed to believe that pre-human ancestors arose and parted ways with apes not in Africa but in Europe. See Jonathan Wellss comments of earlier today on fossils and human origins.

Equally unenlightening, in a different way, is the latest Gallup polling data on belief in evolution, announcing In US, Belief in Creationist View of Humans at New Low. I understand that surveys like this ask the same questions year after year in order to track major trends in opinion. In this case, unfortunately, the question reflects the primitive nature of the evolution debate when Gallup first started polling on it.

They report:

The percentage of U.S. adults who believe that God created humans in their present form at some time within the last 10,000 years or so the strict creationist view has reached a new low. Thirty-eight percent of U.S. adults now accept creationism, while 57% believe in some form of evolution either God-guided or not saying man developed over millions of years from less advanced forms of life.

So they are juxtaposing creation with evolution. Since 1982 theyve been asking:

Which of the following statements comes closest to your views on the origin and development of human beings 1) Human beings have developed over millions of years from less advanced forms of life, but God guided this process, 2) Human beings have developed over millions of years from less advanced forms of life, but God had no part in this process, 3) God created human beings pretty much in their present form at one time within the last 10,000 years or so?

What I wish they would ask is:

Which of the following statements comes closest to your views on the origin and development of living creatures 1) Animal and human life arose and developed over billions of years, guided by a designing intelligence, whether God or otherwise, 2) Animal and human life arose and developed over billions of years, by strictly blind, natural processes, unguided by any intelligent agent, 3) God created all animal and human life at one time within the last 10,000 years or so?

Now that would tell you a lot about the state of the evolution debate. But the modern intelligent design movement didnt exist 35 years ago, so Gallup is stuck in 1982.

That doesnt stop them from trying to insert ID after the fact. They assert, Often rebranded as intelligent design, especially as it relates to education, the creationist viewpoint has met defeat in the Supreme Court but continues to surface in curricula across the U.S.

No. This is of course false. Are they also taking dictation from the National Center for Science Education? ID is not rebranded creationism the ideas are worlds apart. Teaching creationism in public schools has indeed been rejected, but ID is not creationism. ID does not surface in curricula across the U.S. Its not in public school curricula anywhere.

The idea of allowing teachers to challenge students with a range of mainstream evidence about evolution, not ID, has had notable success in a number of states. But that, again, is a different matter. I wont rehash the rest here. See our Science Education Policy.

It sure would be helpful if a major polling company like Gallup refreshed their awareness of the evolution debate next time they survey about it.

Photo: Lower jaw, Graecopithecus freybergi, by Wolfgang Gerber, University of Tbingen, via Science Daily.

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Latest Gallup Polling on Evolution Fails to Enlighten - Discovery Institute

Mike Evans amassed 1,321 receiving yards last year, which ranked fourth in the NFL and made him one of 23 wide receivers to surpass the 1,000-yard mark. However, the Tampa Bay Buccaneers' star pass-catcher cracked four digits in a way that was significantly different from the other 22 players on that list.

Specifically, Evans consistently worked farther downfield than most receivers, on average, frequently getting open in the intermediate-passing range. And when he was less than fully open, when passes were contested, often in the end zone, he helped out his quarterback by frequently winning those battles. He tied for second in the NFL in catches made on third down but, more significantly, turned all 28 of those receptions into first downs. Nobody else in the NFL even turned 90% of their third-down grabs into first downs.

READ: WINSTON MAKES NFL'S TOP 100

All of that paints a picture of a receiver who is excellent at providing Y@C, or yards at catch. His 1,152 Y@C led the entire NFL. The flip side of this stat is YAC, or yards after the catch. In that regard, Evans' average of 1.8 yards after catch was easily the lowest of all 23 of those 1,000-yard receivers. That was somewhat a function of the Bucs' offensive approach, not to mention Evans' great work in the end zone. Most of his 12 touchdowns were on passes that went into the end zone. By definition, a catch made in the end zone will get you six points but it will never get you a single yard after the catch.

So it's hard to excel in both categories, YAC and Y@C. Evans's new teammate, DeSean Jackson, is a notable exception. He ranked third in the NFL in Y@C in 2017 while still posting an above-average 5.1 YAC mark. Since he entered the league in 2008, Jackson has ranked seventh in the NFL in Y@C and fifth in the NFL in YAC. That's a remarkable combination that indicates he's adept at both getting behind the defense and turning short passes into long gains.

Evans is not the same type of receiver as Jackson, so he's not likely to match that dual Y@C/YAC performance. However, he does think he can improve significantly on gaining yards after the catch, and that's a top priority for him in 2017. In April, as he prepared to build on three straight 1,000-yard seasons to open his career, Evans was asked the one thing he hopes to improve in his game this year. His answer was succinct:

"My explosiveness and yards after the catch," he said.

Opposing defenses should be concerned. In much the same way quarterback Jameis Winston obsesses over fixing any flaws in his game, Evans has proved he can identify and eliminate a shortcoming in his own body of work. A year ago at this time, he was working on being a more reliable target for Winston after dropping more passes than he would have liked in 2015. It worked. Evans also thought he could be a more consistent player for Winston by better controlling his emotions during games. That too was noticeably better in 2016. The result was Evans becoming the Buccaneers' most consistently player on offensenot to mention a Pro Bowler for the first time.

Now, with the urging of Offensive Coordinator/Wide Receivers Coach Todd Monken, Evans is setting his sights on jacking up his YAC.

READ: MCCOY MAKES NFL'S TOP 100

"I think the biggest thing is his ability to one is his route running and his run after catch," said Monken. "I think he has more in the tank with him because he does have a natural, competitive-grit side to him that he should be better with the ball in his hands. I think as he gets more and more comfortable I think last year was a piece of, 'OK, lets get better at catching it. Lets eliminate some of the drops that youve had that have led to stopped drives.' OK, so we got that somewhat corrected. Now, how do we get to where we can utilize your competitive spirit, your ability to run after catch?"

Monken said that Evans has dropped a little weight and has looked sharp in the offseason. The 23-year-old receiver is taking his competitive nature on the field and applying it more to the work that takes place between January and September. Evans is working on improving in that split-second after the catch, when you turn quickly and push upfield. That involves working with chains and resistance bands and the ilk.

"My workouts have been a little different, Ive been doing things with like, pulling things and working my yards after catch," said Evans. "Other than that, Ive just been like changing up my workouts. I havent really gotten any advice on how to be explosive."

If Evans is truly determined to improve his results once the football in his hands and in the process potentially take his game to an All-Pro level it would be unwise to bet against him. Evans may have learned how to channel his passion in 2016 and make it more constructive than destructive, but that fire still burns in him.

Im competitive at anything and that just like, drives me," said Evans. "Thats why I get so, you know, on the field I have that emotion. This past year I think I did a good job of channeling that, having passion over emotion like Coach Dirk (Koetter) always says. But I just love competing at anything."

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Mike Evans' Next Evolution: YAC - Buccaneers.com